This invention relates to an improved vessel for containing and handling molten materials and a method for cooling such a vessel. The invention is directed particularly to covers for vessels for molten metals such as melt furnaces, ladles and the like.
Prior art systems for containing molten materials, and in particular, molten metals, have relied on refractory lining or water cooling or a combination of both to protect the walls, bottom and covers of such vessels from the high temperature generated by the molten materials and off-gases. In the case of molten metals such as steel, these temperatures may be in excess of 2800.degree. F. (1540.degree. C.).
Refractory linings installed in such vessels are costly and have short lives, even where such linings are utilized above the melt line of the vessel. Although water has been utilized to cool the inner surfaces of these vessels (generally made from structural steel plate) it has been the usual practice to utilize closed systems in which pressurized water completely fills circulating passages within the vessel walls, roof, etc. These systems generally necessitate high volumes of water at relatively high pressures. "Hot spots" created on the inner wall by blockage of coolant water can lead to flashing of the water to steam and rupture of the containment structure. Once leakage occurs in the inner walls of the vessel, the flow of the cooling water into the molten material can lead to serious hazards such as explosions due to the water flashing to steam or other adverse reactions. These problems create serious hazards to life and equipment in addition to damage to the molten material being processed. Other prior art systems which seek to alleviate such problems utilize complex, costly and difficult-to-maintain equipment which is clearly not desirable in the surrounding area and environment of steel furnaces and other molten material handling vessels.
Bearing in mind these and other disadvantages of the prior art, it is therefore an object of the present invention to provide a relatively lightweight, simple yet effective system for cooling the roof, walls and other containment surfaces of vessels used in handling molten materials, especially melt furnaces.
It is another object of the present invention to provide such a system which, in case of error, minimizes the risks of injury to life and equipment.
It is a further object of the present invention to provide an improved system which reduces the volume of coolant needed within the containment roof and/or walls of a molten material handling vessel.
It is yet another object of the present invention to provide a cooling system which eliminates the need for an installed refractory thermally insulating lining on the interior of the containment roof of such vessels.